Medical professionals use various optical devices for research, diagnosis, detection, treatment, and therapy. Such optical devices generate, condition, and/or deliver light that may be used to optically stimulate nerves or correct eyesight, for example. Typically, medical researchers do not have the measurement devices necessary to determine how far the light penetrates into a tissue or what cross-sectional area is illuminated. To determine these quantities, the researcher needs to measure power, beam diameter and shape, divergence, and wavelength, as well as the optical properties of the tissue in question.
U.S. Pat. No. 6,475,800 issued to Hazen, et al. on Nov. 5, 2002 entitled “Intra-serum and intra-gel for modeling human skin tissue” and is hereby incorporated by reference. Hazen et al. describe a class of samples that model the human body and are based upon emulsions of oil in water with lecithin acting as the emulsifier. These solutions that have varying particle sizes may be spiked with components (albumin, urea and glucose) to simulate skin tissues, and used in the medical field where lasers and spectroscopy-based analyzers are used in treatment of the body. Hazen et al. say that the samples allow one to gather data on net analyte signal, photon depth of penetration, photon radial diffusion, photon interaction between tissue layers, photon density (all as a function of frequency) and on instrumentation requirements such as resolution and dynamic range.
U.S. Pat. No. 6,224,969 issued to Steenbergen, et al. on May 1, 2001 entitled “Optical phantom suitable for stimulating the optical properties of biological material and a method of producing said phantom” and is hereby incorporated by reference. Steenbergen, et al. describe an optical phantom for simulating optical properties of biological material and a method of making the phantom, which includes a matrix of poly(vinyl alcohol) (PVA) and spherical particles whose refractive index differs from that of the PVA. Preferably the PVA has a level of hydrolysis of >98%, and the spherical particles are hollow polystyrene particles. In addition, light-absorbing and light-scattering substances may be added.
U.S. Pat. No. 6,353,226 issued Mar. 5, 2002 and U.S. Pat. No. 6,630,673 issued Oct. 7, 2003 to Khalil et al., both titled “Non-invasive sensor capable of determining optical parameters in a sample having multiple layers,” and are hereby incorporated by reference. The apparatus measures light that is substantially reflected, scattered, absorbed, or emitted from a shallower layer of the sample of tissue, measures light that is substantially reflected, scattered, absorbed, or emitted from a deeper layer of the sample of tissue, determines at least one optical parameter for each of these layers, and accounts for the effect of the shallower layer on the at least one optical parameter of the deeper layer.
U.S. Pat. No. 5,261,822 to Hall, et al. issued Nov. 16, 1993 entitled “Surgical refractive laser calibration device”, and U.S. Pat. No. 5,464,960 issued to Hall, et al. on Nov. 7, 1995 entitled “Laser Calibration Device” which are both hereby incorporated by reference, each describe a phantom cornea for calibrating surgical lasers is formed by superimposition of thin-films of alternating colors. After ablation by a laser beam, the resulting spherical cavity appears as a pattern of nested circles whose concentricity and spacing reflect the alignment and intensity of the laser beam.
U.S. Patent Publication US 2005/0142344 by Michael Toepel entitled “Laser Test Card” is hereby incorporated by reference. Toepel describes a card for testing and displaying a shape of a laser beam.
U.S. Pat. No. 5,480,482 that issued to Novinson on Jan. 2, 1996 entitled “Reversible thermochromic pigments”, is incorporated herein by reference, and describes a color changing pigment composition which changes color reversibly when ted comprising (a) a cyclic aryl lactone dye, (b) a diaminoalkane activator and (c) an ester. The pigment composition can also include a white pigment such as titanium dioxide as an opacifier or a yellow dye such Hansa yellow G. The pigment composition changes from a dark color, e.g., blue, to white when the composition is heated to a specified temperature, e.g., to a temperature of 52 degrees C., and reversibly changes from white back to the blue color when the pigment composition is cooled, e.g., to a temperature below about 25 degrees C.
U.S. Pat. No. 6,669,765 that issued to Senga, et al. on Dec. 30, 2003 entitled “Thermochromic dry offset ink, and printed article produced using the same”, is incorporated herein by reference, and describes a thermochromic dry offset ink comprising a dry offset ink medium and a thermochromic pigment material dispersed therein, wherein the thermochromic pigment material is a pigment material which has a microcapsular form having non-round particle cross section and has a thermochromic material enclosed in the microcapsules. Also disclosed is a printed article produced using the ink. The thermochromic dry offset ink can more improve pressure resistance and heat resistance and also can more satisfy uniform printability and high-speed continuous printability in offset printing especially on articles such as containers.
U.S. Pat. No. 4,681,791 that issued to Shibahashi, et al. on Jul. 21, 1987 titled “Thermochromic textile material”, is incorporated herein by reference, and describes a textile material in the form of fiber, raw stock, yarn or fabric, which comprises fibers each of which is coated with a thermochromic layer containing a thermochromic pigment having a particle size satisfying [a particular formula] of a fiber. The textile material can undergo reversible color change in a wide variety of colors and can be applied to any kind of textile products.
U.S. Pat. No. 6,444,313 that issued to Ono, et al. on Sep. 3, 2002 entitled “Thermochromic acrylic synthetic fiber, its processed article, and process for producing thermochromic acrylic synthetic fiber”, is incorporated herein by reference, and describes a thermochromic acrylic synthetic fiber comprising an acrylonitrile polymer in which a thermochromic pigment composition with an average particle diameter of from 0.5 micron to 30 microns is dispersedly contained in an amount of from 0.5% by weight to 40% by weight based on the weight of the polymer, and being made into fibers; the pigment composition containing (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound and (c) a reaction medium that determines the temperature at which the color-developing reaction of the both compounds takes place. Also disclosed are a processed article of the above thermochromic acrylic synthetic fiber, and a process for producing the thermochromic acrylic synthetic fiber.
U.S. Pat. No. 7,040,805 that issued to Ou, et al. on May 9, 2006 titled “Method of infrared thermography”, is incorporated herein by reference, and describes “A method of infrared thermography is described. The invention utilizes a high resolution infrared thermography system with an infrared camera and associated computer in conjunction with a test chamber to determine heat-transfer coefficients and film effectiveness values from a single test.
U.S. Pat. No. 6,585,411 that issued to Hammarth, et al. on Jul. 1, 2003 titled “Aerosol dispenser temperature indicator”, is incorporated herein by reference, and describes a liquid crystal temperature indicator, and aerosol dispensers equipped with a properly placed indicator, to facilitate using aerosols within preferred temperature ranges or at optimum temperatures. The temperature indicator uses different colors to graphically illustrate temperatures and/or temperature ranges, as well as temperatures above and below optimal temperatures or preferred temperature ranges. Temperature indicators are reusable; they may be self-adhesive and may optionally be transferred from a liquid crystal temperature indicator is either permanently or reversibly adhered to the outer surface of an aerosol dispenser in a location that will allow estimation of the temperature of the liquid inside the dispenser. Liquid crystals are composed of elongated organic molecules that can exhibit different physical properties (e.g., optical and electrical properties) at different temperatures. Using, for example, changes in the color of a plurality of liquid crystals at different temperatures arranged in numerical (i.e., ascending or descending) order, temperature indicators of the present invention can be coupled to aerosol dispensers to indicate desired temperature adjustments to a dispenser within a range of temperatures. The temperature indicators thus act as guides for the use of appropriate heat flow control methods for achieving preferred temperature conditions for making and using aerosol. United States Patents related to temperature measurement using liquid crystals include U.S. Pat. No. 4,064,872 (Caplan), issued Dec. 27, 1977; U.S. Pat. No. 6,257,759 (Witonsky, et al.), issued Jul. 10, 2001; U.S. Pat. No. 6,294,109 (Ratna, et al.); and U.S. Pat. No. 6,284,078 (Witonsky, et al.), issued Sep. 4, 2001, each of which is incorporated herein by reference.
In an article by Passos D. et al., “Tissue phantom for optical diagnostics based on a suspension of microspheres with a fractal size distribution,” J Biomed Opt. 2005 November-December; 10(6):064036 (which is hereby incorporated by reference) there is a description of a phantom for reproducing the phase function, absorption, and scattering coefficients of a real biological tissue (adult brain white matter and liver) using a suspension of polystyrene microspheres with a fractal size distribution. The design of a light scattering goniometer with a cylindrical cell in air is discussed, and phase function measurements using the device are described.
The paper by Viator J A, et al., “Spectra from 2.5-15 microns (i.e., micrometers) of tissue phantom materials, optical clearing agents and ex vivo human skin: implications for depth profiling of human skin,” Phys Med Biol. 2003 Jan. 21; 48(2):N15-24 (which is hereby incorporated by reference) describes tissue phantoms for human skin in the IR wavelengths; it also details the constituents used for the phantom and their relation to the optical properties. They used Fourier-transform infrared spectroscopy in attenuated total reflection mode to measure the infrared absorption spectra, in the range of 2-15 microns, of water, polyacrylamide, Intralipid, collagen gels, four hyperosmotic clearing agents (glycerol, 1,3-butylene glycol, trimethylolpropane, Topicare), and ex vivo human stratum corneum and dermis.
Papers by Nakagawa A., et al., “Pulsed holmium:yttrium-aluminum-garnet laser-induced liquid jet as a novel dissection device in neuroendoscopic surgery.” J. Neurosurg. 2004 July; 101(1):145-50 and Nakagawa A., et al., “Holmium: YAG laser-induced liquid jet knife: possible novel method for dissection.” Lasers Surg Med. 2002; 31(2):129-35 (which are hereby incorporated by reference) describe use of the Ho:YAG in neuroendoscopic ablative surgery applications for small-vessel ablation. This would be useful for muscle tissue phantoms, since blood vessels are made up of smooth muscle. The authors of the first paper describe experiments aimed at solving problems associated with pressure-driven continuous jet of water for neuroendoscopic dissection by using a pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced liquid jet (LILJ). They examined its mechanical characteristics and controllability in an artificial tissue phantom (10% gelatin of 1-mm thickness). The authors of the first paper describe the effect on artificial organs made of 10 and 30% (w/v) gelatin, each of which represent features of soft tissue and blood vessels.
The paper by Ovelmen-Levitt J., et al., “Brain ablation in the rat cerebral cortex using a tunable-free electron laser,” Lasers Surg Med. 2003; 33(2):81-92 (which is hereby incorporated by reference) describes research done at Vanderbilt using their MARK III free electron laser (FEL) tuned to molecular vibrational absorbance maxima in the infrared (IR) wavelength range of 3.0-6.45 microns to study the effect of these various wavelengths and a power level of 5 mJ/2 microseconds macropulse on photoablation of CNS (central-nervous-system) tissue.
There are relatively high costs and various difficulties encountered using the above methods and apparatus. Accordingly, there is a need for an apparatus and method that, in a standardized manner, can cheaply, easily, and directly characterize the optical sources used in optical devices and their interactions with different types of tissue.